This week on Our World: a step toward a better treatment for a nasty parasitic disease ... new evidence that liquid water once flowed on Mars ... and today's young, multitasking generation ...

TAPSCOTT: "They come home and they turn on their computer and they are in three windows talking to their friends and listening to mp3 files. And - oh yeah - they are doing their homework. The big idea is that these kids are different."

Those stories, a greener concrete made with the wastes from rice processing, and more.

Just over a year ago, NASA's Phoenix spacecraft landed on Mars, to hunt for evidence of water on the Red Planet.

Cameras and other instruments found ice and even observed falling snow, and now researchers studying the data have concluded that the area where it landed, near Mars's north pole, does show evidence of liquid water - in the past.

Writing this week in the journal Science, Peter Smith and colleagues note that the ancient water flows were inferred, indirectly, by an analysis of the Martian soil. Smith says the evidence was compelling:

SMITH: "And what we found is that there's calcium carbonate in the soil at the level of about 4 percent. Calcium carbonate typically forms in liquid water. We found that the soil does release water as you heat it up. And we've seen snow falling which, if the climate were just maybe a few tens of degrees warmer, you could actually imagine that snow melting."

Peter Smith is a senior research scientist at the Lunar and Planetary Laboratory of the University of Arizona.

Water is a necessary element of life as we know it. In a Science magazine podcast, Smith addresses the question of whether the apparent history of water on Mars indicates that the planet might have once supported life.

SMITH: "Well, it's hard to say if life is actually associated with these soils. In fact, we have no evidence to talk about life itself. But we see a lot of the ingredients that life needs. And therefore, in a warmer and wetter climate, this really could be a soil that is habitable."

If, or maybe I should say when astronauts get to Mars, they'll likely be thirsty after a months-long spaceflight.

Although the Phoenix spacecraft detected evidence of liquid water in the past near the Martian north pole - and found water ice there today - Peter Smith says that doesn't mean it's the best place for astronauts to set up camp, since conditions during Martian winters will be so harsh.

SMITH: "So I would suggest that astronauts go more the equator and try and find an underground aquifer, where you can drill down to water and bring it up to the surface. And I think that's really what we should be looking for as we think about colonization of Mars."

Peter Smith of the University of Arizona.

Closer to home, but still a long way off ... NASA's Lunar Reconnaissance Orbiter went into orbit around the Moon in late June, and the spacecraft is now undergoing a technical shakedown before it begins its year-long mission of creating a three-dimensional map of the lunar surface. It will provide images at a very high, one-meter resolution, in part to help spaceflight planners pick a landing spot for the next human expedition to the moon.

Researchers create genetic map of disease-causing parasite

Researchers have created a genetic map of the freshwater parasite that causes schistosomiasis, a chronic and painful disease that causes tens of thousands of deaths each year. As VOA's Jessica Berman reports, scientists hope their work will lead to more treatments for the disease that affects an estimated 200 million people worldwide.

BERMAN: Experts consider schistosomiasis the second worst parasitic illness after malaria. The disease is spread by human contact with parasites that are carried by certain freshwater snails. The disease can permanently damage the lungs, kidney, liver, and intestines, and could ultimately result in death.

Schistosomiasis is found in about 70 tropical and sub-tropical countries and is a particular problem in sub-Saharan Africa, where an estimated 180 million people are infected with the disease.

Since the 1980s, the drug of choice to treat the disease has been praziquantel. But researcher Tim Anderson says the schistosome parasite is starting to show signs of resistance to the drug.

ANDERSON: "Many people in the field feel that this is really a disaster waiting to happen."

BERMAN: Anderson, a scientist at the Southwest Foundation for Biomedical Research in San Antonio, Texas, cites the experience with malaria, in which the standard treatment, chloroquine, is now ineffective in many parts of the world. Anderson says that to avoid a similar outcome in the treatment of schistosomiasis, new drugs must be developed before the parasites acquire widespread resistance to praziquantel.

Anderson and his colleagues have drawn a genetic roadmap of the schistosome parasite - the first DNA blueprint created for a parasitic worm. He says researchers hope to pinpoint the genetic mutations that make the schistosome parasite resistant to praziquantel, so they can create new treatments for the disease.

ANDERSON: "If we can understand how resistance is operating, then it may be a question of simply altering a few, say, side groups on the existing drugs to restore efficacy. So we are hoping minor tweaks to existing drugs maybe provide a simple solution."

BERMAN: Praziquantel treatment for schistosomiasis is relatively cheap. And experts involved in the battle against the parasite worry that a replacement drug might be too expensive to reach the millions of people who need it.

BERMAN: Tim Anderson and his colleagues at the Southwest Foundation for Biomedical Research are applying for grant money to support further study of possible genetic mutations that could make the parasitic worm resistant to drug treatment. The researchers describe the genetic blueprint of the schistosome parasite in the journal Genome Biology. Jessica Berman, VOA News, Washington

Scientists probe link between pond scum, degenerative illness

There's a kind of blue and green scum that can bloom in lakes and ponds. This scum is called cyanobacteria. For years, scientists have known that it can produce dangerous toxins. Researchers are investigating whether there might be a link between cyanobacteria and the disease called amyotrophic lateral sclerosis, or ALS - also known as motor neuron disease or, here in the U.S., Lou Gehrig's disease, after a famous baseball player who died of the ailment. Amy Quinton has the story.

QUINTON: Jody Conner reaches into his refrigerator in his lab.

CONNOR: "This is the cyanobacteria that we've collected. This one comes from Harvey Lake in Northwood. See how green that sample is?"

QUINTON: He's the Director of New Hampshire's Limnology Center.

Conner has been collecting samples of cyanobacteria from lakes across New Hampshire.

It looks like green, scummy algae on the surface of the water, but it's actually bacteria.

Conner says cyanobacteria feed on nutrients like phosphorus and nitrogen that can come from runoff of lawn fertilizers or sewage.

CONNER: "They need sunlight, phosphorus, and they seem to like the warmer waters. So, they really grow in mass numbers when they have all three of those."

QUINTON: Jim Haney is a professor of biological sciences at the University of New Hampshire.

He says, in high enough concentrations, some cyanobacteria blooms can produce more than 70 different kind of liver toxins called microcystins.

HANEY: "That scum can be toxic enough that it's been estimated that only about 17 milliliters is enough to kill a small child. 17 milliliters is just a couple of teaspoons."

QUINTON: Cyanobacteria blooms can also produce neurotoxins.

Haney, and other researchers, have embarked on research to find out if there's a connection between cyanobacteria and patient's with ALS.

The research began when Dr. Elijah Stommel began mapping hundreds of ALS patients across New Hampshire.

Stommel is a neurologist at Dartmouth Hitchcock Medical Center.

He noticed the incidence of ALS was 2.5 times greater than the national rate around lakes known to have had significant cyanobacteria blooms.

Stommel says he found a particularly high cluster of patients on one lake in the western part of the state.

STOMMEL: "We were able to establish that there appeared to be about a 25 fold increase in what one would expect to see for the ALS incidence."

QUINTON: But he's not sure if cyanobacteria are the culprit.

A few scientific studies have shown a particular type of neurotoxin found in cyanobacteria is also found in patients with ALS. The neurotoxin is known as BMAA. But it's not known whether BMAA can trigger ALS.

Jim Haney says more research is needed.

HANEY: "We know that, in the laboratory, a wide range of different types of cyanobacteria are able to produce BMAA. So, one of our goals this summer is to determine whether there are BMAA molecules in our lakes."

QUINTON: So far, researchers haven't found BMAA, and there are still a lot of unknowns about how people could be exposed.

Do you have to drink it or can you breathe it in the air? How long do you need to be exposed to it before it causes damage? Again, Dr. Elijah Stommel.

STOMMEL: "If there is a link between cyanobacteria blooms and the toxins they make, and a neurodegenerative disease like ALS, then I think we should pursue that with as much vigor as we can. And I think the neurology literature would suggest there is an environmental trigger for ALS."

QUINTON: But scientists have not yet found that link. If they do, Stommel says that link might help find ways to prevent the dangerous toxins, or block their effects.

For The Environment Report, I'm Amy Quinton.

Support for The Environment Report comes from the Park Foundation, and the Gaylord and Dorothy Donnelley Foundation. You can hear the Report, and subscribe to the daily podcast, at EnvironmentReport.org.

America's founding charters on our Website of the Week

It's time again for our Website of the Week, when we showcase interesting and innovative online destinations.

Our national holiday, Independence Day, is July 4. Many of us Americans will celebrate with parades and picnics and fireworks. Here in Washington, people will line up at the National Archives to see what are called the Charters of Freedom. For those who can't come in person, our Website of the Week is the next best way to see these key documents in the forging of the American nation.

STANWICH: "The Declaration of Independence is the document that declared our freedom from England, from the King of England. The Constitution is really the blueprint for the United States government. The Bill of Rights was created to protect individual freedoms, like the freedom of speech, the freedom of religion, the freedom to assemble - rights that weren't specifically written in the Constitution itself."

You can see and learn more about the Charters of Freedom at archives.gov/exhibits/charters.

While there is no substitute for the thrill of seeing the original, two century old documents, Maria Stanwich of the U.S. National Archives explains that the website offers in some ways a richer experience. For example, the shrine-like rotunda where the originals are displayed has murals depicting the signing of the historic documents.

OLAUSSON: "But if you go to the website, you can see those same murals on the website, and you can learn more about those signers. You can read the actual biographies of those signers and learn about the struggles and the life that they had, and what they lost at the end of their struggle."

The Charters of Freedom may be the National Archives' most famous documents, but Maria Stanwich says there's lots more to look at online.

STANWICH: "There are other exhibits that you can see on that same website. All of our exhibits, or most of them, are documented and then put on the website for people around the world who can't come and visit us to see them."

See for yourself at archives.gov/exhibits/charters, or get the link to this and some 250 other Websites of the Week from our site, VOAnews.com/ourworld.

Concrete is the world's most popular building material. Rice is one of the world's most abundant food crops. Now, some researchers are putting the two together to try to make concrete more environmentally friendly. VOA's Steve Baragona reports.

BARAGONA: More than 600 million metric tons of rice are grown worldwide each year. After the grain is harvested, though, the rice hulls are mostly considered waste. In many places, farmers burn them, along with the stalks, creating thick smoke that can cause breathing problems. In the United States, rice hulls usually just get thrown away, according to chemist Rajan Vempati at the ChK Group, an engineering firm.

VEMPATI: "It ends up in landfills or is used as poultry or animal litter. It has no high-tech application."

BARAGONA: But Vempati and his colleagues would like to change that. They want to use these rice hulls to reduce the amount of carbon dioxide created by making concrete.

The modern world is made of concrete. The mixture of crushed stone and sand is the essential building material for everything from skyscrapers to sidewalks. It's held together with something called Portland cement, and Clemson University engineering professor Prasad Rangaraju says that's where the greenhouse gases come from.

RANGARAJU: "For every ton of Portland cement that we manufacture, we release about a ton of carbon dioxide, which is a greenhouse gas. So if we can replace or reduce the use of Portland cement, we would definitely take the right step in reducing the carbon footprint of concrete."

BARAGONA: With about five billion cubic meters of concrete produced each year, it adds up to about five percent of the world's man-made carbon dioxide production.

But it turns out that when you take Portland cement and add a bit of ash from rice hulls burned in a controlled process, it makes the cement stronger, so you can use less of it. That means producing less carbon dioxide.

The basic idea has been around for centuries, according to Colin Lobo. He's senior vice president of engineering with the National Ready Mixed Concrete Association.

LOBO: "You have to go back to the Romans and when they had volcanic ash."

BARAGONA: Lobo says the Romans discovered that mixing in volcanic ash from the slopes of Mount Vesuvius made their cement stronger. Today, he says, some builders use slag left over from iron-making, or the ash from coal-fired power plants to do the same thing.

LOBO: "Our modern-day volcanoes are essentially the power plants."

BARAGONA: But inventors Vempati and Rangaraju say the advantage of rice hull ash is that, unlike fly ash or slag, it's a renewable product that doesn't generate any additional carbon dioxide. Plus, they say their process makes a light-colored cement that's better at reflecting sunlight, so buildings made with it cost less to air-condition. And this concrete resists corrosion better.

But their success may depend on cost. They developed their process with a grant from the National Science Foundation, and it hasn't been commercialized yet. A different rice hull ash product on the market is relatively expensive. And since transporting rice hull ash would add to the cost, concrete industry expert Colin Lobo says it might not make sense unless rice is grown nearby.

LOBO: "But if it's in an area where they have this in abundance and they can make a valuable product -- for example, they grow a lot of rice in India. So, if they do it in India, and they have a way to [turn] a product that would usually go into a landfill into a beneficial use, then that would be great."

BARAGONA: Vempati and Rangaraju would like to develop a small, portable processing unit that could be taken to the many small farms in countries like India or China, where the ash could be used locally. Steve Baragona, VOA News, Washington

Technology, Internet put powerful stamp on today's youth

The newest generation of young adults is the first to have grown up with the Internet and social networking as a basic feature of their lifestyles and ways of thinking, relating and innovating. A new book, Grown Up Digital, explores the many powerful new ways that youth, technology and society are coming together. Adam Phillips reports.

PHILLIPS: Don Tapscott is an optimist about youth and the future. And in his newest book, "Grown Up Digital," it's clear the business strategist believes the world's first truly global, digitally "switched on" generation has finally come of age.

TASPSCOTT: "When I was growing up, my generation, the Boomers, watched 24 hours a week of television per kid. These kids watch less TV and they watch it differently. They come home and they turn on their computer and they are in three windows talking to their friends … and they are listening to mp3 files with their video game going on the side. And - oh yeah - they are doing their homework, and the television is in the background. It's sort to like ambient media or Muzak. The big idea is that these kids are different!"

PHILLIPS: Tapscott's new book is subtitled, "How the Net Generation is Changing Your World." In it, he cites recent research from the University of Rochester's Brain and Vision Lab suggesting that interactive technology can literally change the brain. Researchers found that regular video gamers notice more detail in their visual field, and that their brains process visual information more quickly than non-users.

TASPSCOTT: "And this is creating brains more appropriate for the 21st century. So this is good."

PHILLIPS: Tapscott led an effort to interview nearly 6,000 young people between the ages of 12 and 31 in ten countries. The project revealed several similar attitudes and behavior patterns among what Tapscott calls "NetGeners." For example, they expect greater fluidity and freedom of choice in how they live and who their friends and associates are than previous generations did. They also love to customize.

TASPSCOTT: "They change their handle, their desktop, their screen saver, their Facebook profile. You name it. They can interact with and transform the world of their media."

PHILLIPS: What's more, Tapscott says, young people expect and demand entertainment and play in almost everything they do.

TASPSCOTT: "Sixty percent say having fun with a service or a product is as important as what the product or service does. They don't want to be passively 'sold to.' They want to be able to interact with companies and with brands, not just be the passive recipients of company stuff."

PHILLIPS: Perhaps the most revolutionary place where young people expect a good time is at work.

TASPSCOTT: "For this generation, they want work to be the same thing as fun. And of course the kids have got it right! Work and learning in a knowledge economy are the same thing."

PHILLIPS: Mobility is another common feature of the Net Generation lifestyle. Tapscott says that by the time they're 27, a majority of Americans are already on their third job. And because so much of their work is being done online and collaboratively, rapid change is also occurring in corporate culture and other areas.

TASPSCOTT: "There are uniquely qualified minds just itching to solve the world's problems, not just problems of corporations, but problems in every sphere of society, we're in the early days of some profound changes that I hope will help us address the vexing challenges of this ever-shrinking world."

PHILLIPS: But Don Tapscott recognizes that this new digital world has its hazards. He is concerned, for example, that NetGeners may be too quick to share compromising private information about themselves on social networking sites. Also, he acknowledges the large "digital divide" between young people in developed nations, and their peers in the developing world. However, he says the rapid growth in the number of Internet users in China and Africa over the past decade is a healthy sign, and he hopes that this trend will continue to accelerate.

This is Adam Phillips reporting from New York.

MUSIC: "Our World" theme

That's our show for this week.

If you'd like to get in touch with us, our email address is ourworld@voanews.com. Or use the postal address -

Our World Voice of America Washington, DC 20237 USA

Our World is edited by Rob Sivak. Bob Doughty is the technical director.

And this is Art Chimes inviting you to join us online at voanews.com/ourworld or on your radio next Saturday and Sunday as we check out the latest in science and technology ... in Our World.